The area of the workforce that women don't want to be part of, such as digging, road construction, garbage dumping, etc. as oppose to glass ceiling jobs such as, being CEO, chairman, congressman, president, and all that good stuff. Due to political correctness, it's harder for men to get most medium paying jobs, so some are stuck under the glass cellar. basically men dominate both extremes of the spectrum.

They put more cracks in the glass ceiling than they did in the glass cellar.

From a news source:
The advertisements that ran on about 200 buses across the city in recent months carried posters displaying a suggestively posed woman in hot pants kneeling among a pile of books beside the snappy slogan "Read Books, Get Brain."